AT77.01 Telecommunication Networks

August Semester, 2008

AT77.01 : Telecommunication Networks 3(3-0)

• This course is to provide the understanding of the evolution of telecommunication networks from Plain Old Telephone System (POTS) to present-day convergence of fixed and mobile networks (wired and wireless networks).

• An overview on the Role of Telecommunications in Developing Countries, Telecommunications Organizations, Telecommunication Standardizations and Services is also provided.

• Role of Telecommunications in Developing Countries

• Telecom Organizations and Standardization

• Public Switched Telephone Network (PSTN)

• Signal Transmission over the Network

• Switching and Signaling

• Multiplexing of Analog and Digital Signals

• Line-of-Sight Radio Relay Links

• Satellite Links

• Optical Links

• Mobile Communications Network

• Internet Technology

• Broadband Access Networks

• Emerging Wireless Networks

Telecommunications(‘Tele’-means ‘over a long distance’; or ‘far’)

Telecommunications Network (TN)

• TN is one of the most complex systems in present day.

• Services provided through TN have essential impact on the development of the community.

• TN is considered as one of the most essential infrastructure components for the development of a country.

Role of TN in Everyday Life• Everyday voice communications, TV, Radio, Data,

Internet• Banking, automatic teller machines, telebanking; • Aviation, booking of tickets:• Sales, wholesale, and order handling; • Credit card payments at shops;• Booking hotel rooms by travel agencies; • Material purchasing by industry; • Government operations, such as taxation, e-governance• All e-business and e-services• And many, many other services

OSI Model

Data unit Layer Function

7. Application Network process to application

6. Presentation Data representation and encryption

5. Session Interhost communication

Segments 4. Transport End-to-end connections and reliability (TCP)

Packets 3. Network Path determination and logical addressing (IP)

Frames 2. Data link Physical addressing (MAC & LLC)

Bits 1. Physical Media, signal and binary transmission

Medialayers

DataHostlayers

Network (Layer 3)

This layer provides switching and routing technologies, creating logical paths, for transmitting data from node to node. Routing and forwarding are functions of this layer.

Data Link (Layer 2)

At this layer, data packets are encoded and decoded. It handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sublayers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sublayer controls how a source on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.

Physical (Layer 1)

This layer conveys the bit stream - electrical impulse, light or radio signal -- through the network at the electrical level.

Communication Protocols

A protocol is a convention or standard that controls or enables the

connection, communication, and data transfer between two endpoints. In its

simplest form, a protocol can be defined as the rules governing the whole

process of communications. Protocols may be implemented by hardware,

software, or a combination of the two. At the lowest level, a protocol defines

the behavior of a hardware connection.

TCP/IP is a very good example of Protocol.

We can say that:

• Telecommunication Network allows us to exchange among ourselves

(or to send/receive only) voice, text message, image, video or any

data signals.

• Telecommunication Network is an aggregation of interconnected

networks of several types.

• Telecommunication Network is circuit-switched or packet-switched

originating from voice signal transmission (telephone network) or

data signal transmission (data network) respectively.

• Presently, all networks have converged into one Global

Telecommunication Network consisting of all types of networks.

So, what is a Telecom Network?

• A Telecommunications Network can be defined as the set of devices, mechanisms, procedures and protocols by which the end-user equipment in the network can exchange information meaningfully.

Functions of Telecom NetworksTypical functions include:• A path by which electrical signals can be

transmitted.• A mechanism by which bits can be converted to

and from electrical signals (in digital systems).• Methods to overcome deficiencies in the

electrical signal path causing error in interpretations.

• Techniques for selecting and maintaining a path through the network to perform the above functions.

Historical Perspectives

1800-1837 Preliminary developments: Volta discovers the primary

battery; Fourier and Laplace present mathematical treatises;

Ampere, Faraday, and Henry conduct experiments on

electricity and magnetism; Ohm's law (1826); Gauss, Weber,

and Wheatstone develop early telegraph systems.

1838-1866 Telegraphy: Morse perfects his system; Steinhill finds that the

Earth can be used for a current path; commercial service is

initiated (1844); multiplexing techniques are devised; William

Thomson calculates the pulse response of telegraph line

(1855); transatlantic cables are installed.

1845 Kirchoff’s circuit laws.

1864 Maxwell's equations predict electromagnetic radiation.

1876-1899 Telephony: Alexander Graham Bell perfects the acoustic

transducer; first telephony exchange with eight lines; Edison's

carbon-button transducer; cable circuits are introduced;

Strowger devises automatic step-by-step switching (1887);

Pupin presents the theory of loading.

1887-1907 Wireless telegraphy: Heinrich Hertz verifies Maxwell's theory;

demonstrations by Marconi and Popov; Marconi patents

complete wireless telegraph system (1897); commercial

service begins, including ship-to-shore and transatlantic

systems.

1904-1920 Communication electronics: Lee De Forest invents the Audion

(triode) based on Fleming's diode; basic filter types are

devised; experiments with AM radio broadcasting; the Bell

System completes the transcontinental telephone line with

electronic repeaters (1915); multiplexed carrier telephony is

introduced: H. C. Armstrong perfects the super heterodyne

radio receiver (1918); first commercial broadcasting station.

1920-1928 Carson, Nyquist, Johnson, and Hartley present their

transmission theory.

1923-1938 Television: Mechanical image-formation system is

demonstrated; theoretical analysis of bandwidth requirements;

DuMont and others perfect vacuum cathode-ray tubes; field

tests and experimental broadcasting begin.

1931 Teletypewriter service initiated.

1934 H. S. Black develops the negative feedback amplifier.

1936 Armstrong's paper states the case of FM radio.

1937 Alec Reeves conceives pulse code modulation.

1938-1945 Radar and microwave systems are developed during World

War II; FM is used extensively for military communications;

hardware, electronics, and theory are improved in all areas.

1945-1948 Arthur C. Clark proposes global communications by using 3

GEO satellites.

1944-1947 Mathematical representations of noise are developed;

statistical methods for signal detection are developed.

1948-1950 C. E. Shannon publishes the founding papers of information

theory; Hamming and Golay devise error-correcting codes.

1948-1951 Transistor devices are invented.

1950 Time division multiplexing is applied to telephony. Hamming

presents the first error-correction codes.

1953 Color TV standards are established in United States.

1958 Long-distance data transmission system is developed for

military purposes.

1960 Maiman demonstrates the first laser.

1961 Integrated circuits are applied to commercial production.

1962 Satellite communication begins with Telstar I.

1962-1966 Data transmission service is offered commercially; wideband

channels are designed for digital signaling; pulse code

modulation (PCM) proves feasible for voice and TV

transmission; theory for digital transmission is developed;

Viterbi presents error-correcting codes; adaptive equalization

is developed.

1964 Fully electronic telephone switching system is put into service.

1965 Mariner IV transmits pictures from Mars to Earth.

1966-1975 Commercial satellite relay becomes available; optical links

using lasers and fiber optics; ARPANET is created (1969) and

followed by international computer networks.

1968-1969 Digitalization of telephone network begins.

1970-1975 Standards of PCM by ITU are developed.

1975-1985 High-capacity optical systems are developed; the breakthrough

of optical technology and fully integrated switching systems;

digital signal processing by microprocessors.

1980-1995 Modern cellular mobile network is put into service: NMT in

Northern Europe and AMPS in the United States; OSI

reference model is defined by International Standards

Organization (ISO).

1985-1990 LANs breakthrough; Integrated Services Digital Network

(ISDN) standardization finalized; public data communication

services become widely available; Optical transmission

systems replace copper systems in long-distance wideband

transmission; SONET is developed; Global System for Mobile

(GSM) and SDH standardization is finalized and first systems

put into commercial use.

1990-1997 The first digital cellular system GSM is put into commercial

use and its breakthrough is felt worldwide; deregulation of

telecommunications in Europe proceeds and satellite- TV

systems become popular; Internet usage and services expand

rapidly because of the WWW.

1997-2001 Telecommunication community is fully deregulated and

business grows rapidly; cellular networks such GSM and

CDMA expand worldwide; Internet traffic exceeds public

switched telephone network (PSTN) traffic; commercial

applications of Internet expand and a share of conventional

speech communications is transferred from PSTN to Internet;

ATM technology makes wide area networks (WAN) networks

wideband; performance of LANs improve with Gbps

technologies.

2001-2008 High-definition TV (HDTV); 3G mobile communication

systems; broadband networks and access systems bringing

new multimedia services available; dominance of wireless

systems like 802.11—(e.g.WLAN, Wi-Fi), 802.15—

(WPAN e.g. Bluetooth, UWB); 802.16—(e.g. WiMAX-

fixed and mobile).

Development of Telecommunications services.

Standardization in Telecommunications

• Communication networks are designed to serve a wide variety of users with equipment from many different vendors.

• To design and build networks effectively, standards are necessary to achieve interoperability, compatibility and required performance in a cost-effective manner.

• Standards (open standards) are needed to enable the interconnections of systems, equipment and networks of different manufacturers, vendors, and operators.

Effects of Standardization• Standards enable competition• Standards lead to economies of scale in manufacturing

and engineering• Political interests often lead to different standards in

Europe, Japan, and America• International standards are threats to the local industries

of big countries but opportunities to the industries of small countries

• Standards make possible the interconnection of systems from different vendors

• Standards make users and network operators vendor independent and improve availability of the systems

• Standards make international services available

Some Examples of International Standards• International telephone numbering, country codes:

without globally unique identification of subscribers, automatic international telephone calls would not be available

• Telephone subscriber interface.• PCM coding and primary rate frame structure: make

national and international digital connections between networks possible.

• Television and radio systems.• Frequencies used for satellite and other radio

communications.• Connectors and signals of PC, printer, and modem

interfaces.• LANs: enable us to use computers from any

manufacturer in our network, for example.

Interested Parties in Standardization

ServiceUsers

EquipmentManufacturers

NetworkOperators

AcademicExperts

Network operators support standardization:

• To improve the compatability of telecommunication systems;

• To be able to provide wide-area or even international services;

• To be able to purchase equipment from multiple vendors.

Equipment manufacturers participate in standardization:

• To get information about future standards for their development

activities as early as possible;

• To support standards those are based on their own technologies;

• To prevent standardization if it opens their own markers.

Service users participate in standardization:

• To support the development of standardized international services;

• To get alternative system vendors (multivendor networks);

• To improve the compatibility of their systems.

Other interested parties include:

• Government officials who are keen on having national approaches

adopted as international standards;

• Academic experts who want to do research in new technological

approaches.

Standardization Bodies

• National Authorities

• Regional Organizations

• Global Organizations

National Authorities

ANSI

SFS

DIN BSI

Some examples of national standardization authorities (BSI, BritishStandard Institute; DIN, Deutche Industrie-Normen; ANSI, AmericanNational Standards Institute; SFS, Finish Standards Institute).

European Organizations

• European Telecommunications Standard Institute (ETSI)

• European Committee for Electrotechnical Standardization/European Committee for Standardization (CEN/CENELEC)

• Conférence Européenne des Administration des Postes et des Tele-communication or European Conference of Posts and Telecommunication Administration (CEPT)

CEN/CENELEC

ETSI CEPT

Committees of ETSI Joint ETSI/ECMA committee (JEEC)

Joint technical committee (ETSI/EBU JTC)

Security algorithms group of experts (SAGE)

Strategic review committee on European information infrastructures (SRC6)

Program advisory committee (PAC)

Network aspects (NA)

Business telecommunications (BTC)

Transmission & multiplexing (TM)

Terminal equipment (TE)

Equipment engineering (EE)

Methods for testing and specification (MTS)

Human factors (HF)

Special mobile group (SMG)

Satellite earth stations & systems (SES)

Radio equipment & systems (RES)

Communication networks & systems interconnection (ECMA TC32)

American Organizations• American National Standards Institute (ANSI) • Institute of Electrical and Electronics Engineers (IEEE) • Electronic Industries Association (EIA) • Federal Communications Commission (FCC)

EIA

IEEE

FCC

Global Organizations

• International Telecommunications Union (ITU) • International Standards

Organization/International ElectrotechnicalCommission (ISO/IEC)

ITU-R (CCIR)ISO/IEC

ITU-T (CCITT)

ITU Structure

PlenipotentiaryConference

ITUCouncil

WorldTelecommunication

StandardizationConferences

World/RegionalRadiocommunication

Conferences

World/RegionalTelecommunication

DevelopmentConferences

TelecommsStandard.

StudyGroups

RadioRegulations

Board

TelecommsDevelopmentStudy Groups

RadiocommsStudy Groups

DirectorBureau

AdvisoryGroup

DirectorBureau

AdvisoryGroup

DirectorBureau

AdvisoryGroup

General Secretariat Coordination Committee

ITU-TTelecommunication

StandardizationSector

ITU-RRadiocommunication

SectorTelecommunication

DevelopmentSector

Structure of the ITU

Examples of ITU-T Study Groups

SG 1 Service definition

SG 2 Network operation

SG 3 Tariff and accounting principles

SG 4 Network maintenance

SG 5 Protection against electromagnetic environment effects

SG 6 Outside plant

SG 7 Data networks and open system communications

SG 8 Terminals for telematic services

SG 9 Television and sound transmission

SG 10 Languages for telecommunication applications

SG 11 Switching and signaling

SG 12 End-to-end transmission performance of networks and

terminals

SG 13 General network aspects

SG 14 Modems and transmission techniques for data, telegraph and

telematic services

SG l5 Transmission systems and equipment

Big Global Operators• INTELSAT• INMARSAT• Vodafone• NTTDoCoMo• AT&T• British Telecom• France Telecom• German Telecom• Telstra• Telenor• TeliaSonera• Satellite based: Globalstar, Iridium, Thuraya, ACeS

Some Interesting Numbers in Telecom Usage

• Almost 40 countries in the world now have more than 100% penetration in mobile phone sector.

• China has over 500 million mobile subscriber at present.

• About 80% of the world’s population is covered by mobile phone, and by 2010, it will be 90%.

• Nokia Corporation was the largest manufacturers of mobile phone having 36% of the device market in the first quarter of 2007.